Problem: Last Monday, William's parents gave birth to twins and named them Michael and Omar. When they were first born, Michael weighed 6.4 pounds and was 18.5 inches tall, and Omar weighed 8.79 pounds. How much did the babies weigh in total?
Explanation: To find the weights of the 2 babies, we need to add their weights together. Michael's weight + Omar's weight = total weight. ${6}$ ${4}$ ${0}$ ${8}$ ${7}$ ${9}$ ${+\vphantom{0}}$ ${9}$ ${1}$ ${5}$ ${1}$ Together, the babies weigh 15.19 pounds.